Meteorite Offers 2-Billion-Year-Old Glimpse of Mars

A meteorite found in the Sahara, one of the oldest ever to come from Mars, offers evidence that life could have existed there more than two billion years ago, researchers say.

The 0.7-pound fragment contains more water than any other known Martian meteorite. “It’s about 6,000 parts per million of water,” said Carl B. Agee, a planetary scientist at the University of New Mexico who led the study. “That’s the water locked into the mineral structure of the meteorite.”

By comparison, there are more than 100 other known meteorites from Mars, and most have a water content of 200 parts per million.

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Scientists are using water recovered from a Martian meteorite to gauge conditions on the planet more than two billion years ago.CreditCarl Agee

The meteorite contains organic carbon similar to that found in other Martian meteorites. But it is 10 times as old, dating from the early part of the most recent geologic epoch on Mars, called the Amazonian. Most other meteorites from Mars are about 200 million years old. The meteorite most likely came from an explosive volcano, Dr. Agee said.

Its unusual composition — cemented fragments of basalt — is consistent with observations made by recent Martian rovers and orbiters.

This led researchers to conclude that the meteorite came from the planet’s crust. The water captured in the meteorite may have come from underground water or surface waters near the explosion, Dr. Agee said.

“The sample may give us an idea of what volcanic activity was like then, but it also gives us a glimpse of what the surface of Mars was like at that time,” he said, adding that the abundance of water “suggests that it’s within the realm of possibility that life could have existed 2.1 billion years ago.”

A version of this article appears in print on , Section D, Page 3 of the New York edition with the headline: Meteorite Offers 2-Billion-Year-Old Glimpse of Mars. Order Reprints | Today’s Paper | Subscribe